Method of preparing gelatin



Patented Feb. 8, 1949 2,460,809 METHOD or PREPARING GELATIN Rudolph E.Damschroder and. Marie E. Kantiman, Rochester, N. Y., assignors toEastman Kodak Company, Rochester, N. Y., a corporation of New Jersey.

No Drawing.

Application February 7, 1946,

Serial No. 646,211 r en the time of treatment sharpeners have been addedto the liming suspension employed for that purpose. After treatment withthe lime, the hide or bone stock may then be treated with acid to removethe lime, followed by extraction of gelatin therefrom with hot water. Inaddition to its being a long drawn-out process, also in the previousoperations, there was often danger of loss of gelatin in the acidtreatment which tends to hydrolyze the collagen present, thus formingmaterial which may be washed out in the washing operations. c 1 J Oneobject of our invention is to provide an improved method of preparinggelatin from gelatin-containing material. Another object of 'ourinvention is to eliminate the liming step in me paring gelatin fromhides or bones. A further object of our invention is to provide a methodof preparing gelatin in which the organic inaterial from which thegelatin is to be obtained is dissolved and the gelatin is separated.there from. Other objects of our invention will appear herein.

We have found that the organic constituents of gelatin-containingmaterials can be dissolved in a water solution of ammonia or a loweraliphatic amine, such as methyl amine, dimethyl amine, or ethyl amine,in which dissolving-operation collagen is converted to gelatin and 1 thegelatin thus obtained can be separated from the solution and employed asdesired.

In proceeding in accordance with our invention, it is desirable that thegelatin-containing materials be first divided into small units'sothatthe dissolving action may readily take place. For instance if theparticles to be treated are 50 mesh or finer, the dissolving action maytake place in a few minutes. If the particles-are as much as 20 mesh,the dissolving action is slower and with still larger units, a stillslower dissolving action occurs. For instance, if a material such ashides be in the form of pieces as much as A inch in diameter, it maytake as much as an hour to dissolve that material. Thedisadvantage-of along time of dissolution is that the material which dissolves first isbeing subjected to-hydrolysis during the dissolving of..the remainder ofthe material and, therefore,;that-gelatin; is

hydrolyzed morethanis desired for, auniform product. If the presence ofsome excessively hy drolyzed gelatin is not objectionable in the finalproduct, the use of small particles of hide or bone as the startingmaterial is not so important.

Our invention is applicable to obtaining gelatin from gelatin-containingmaterials generally, whether wet, dried, or salted, but particularlyfrom bones. The hides employed may be on the one hand green calfskinswon the other hand old, dried hides, such as dried bufialo skins. In thecase ,of calfskins or the like which are more susceptible to thedissolving of organic matter dissolution will take place in a shorttime, whereas with hides which are dry, horny, and thick, the dissolvingaction may be slow, although a fine particle size of this material willspeed up the action. Other gelatin-containing materials, such as rawbones or sinewsJeet, tails, or other parts of cattle, sheep, or otheranimals may be treated by our process, although with many of these thegelatin obtained will not be in nearly as high a degree of refinementwas that obtained:

from for instance, hides.

The agent which is employed to promote the dissolving operation may beammonia or an aliphatic amino compound of notmore than three carbonatoms or a mixture of these agents. Some of the amino compounds whichhave been found to be particularly useful for this purpose are thefollowing: ammonia, methylamine, dimethyls amine, ethylamine, ethylenediamine, ethanolamine, propanolamine, propylene diamine.

It is desirable to have a concentration of at least 10% of the amine orammonia in water in order to promote the dissolving ofthe organic matterof the gelatin-containing material. As a rule, it will be preferable tooperate the process with concentrations of less than 30% of ammonia oramine, We have found, however, that concentrations less than 10% areoperative and their use is within the scope of our invention. Forinstance, a 3% solution may be employed for the dissolving operationalthough a time of two hoursmay be necessary with a readily treatablematerial as compared with 10 or 20 minutes with concentrations of amineor ammonia within the preferred range. The lower limit of concentrationwhich will dissolve the. gelatin-forming material as-specified aboveappears to be about 1% of amine or ammonia. I

Although We have found that the dissolving of that organicmatter ofgelatin-containing material in accordance with our invention takes placesatisfactorily at temperatures in the yicinity :of R, such as l20-140other temperatures may also bee'mploy'e'd, the'time of dissolving thematerial depending not only on thetemperature but also upon thecondition or the material, its particular size, and T the concentrationof a'rnin'e prior art, were ground so that they would pass a mesh finerthan 50. This ground, acidulated bone was agitated in a water solutionof methyl amine of 12% concentration for ten'minutes at 130 F.,whereupon the acidulated bone was dissolved. The thus-formed solutionwas evacuated by means of an aspirator pump to a vacuum of 30-40 mm. ofmercury for twenty-five minutes at 130-140" F. This treatment reducedthe methylamine content to about 1% of the original content ofmethylamine. The pH of the solution was adjusted to 6.0 by the additionof a small proportion of sulfuric acid, and the solution obtained wasfiltered. This solution was then set by cooling and the resultinggelatin obtained was washed and dried. I

Example 2.Ground, acidulated bone was agitated in a 28% solution ofethylamine for ten minutes at 130 F. whereupon a considerable fractionof the bones dissolved, This solution was evacuated by means of anaspirator pump for twenty-five minutes at 130-140. F. This reduced theethylamine content to about 1-2% of the original. The pH of the solutionwas adjusted to 6.0 by addition of sulfuric acid and this solutionfiltered. The chilled set gelatin solution was then dried.

Example 3.--Dry bones as obtained by degreasing bones as described inthe prior art were ground so that they would pass a mesh finer than 50.This ground non-acidulated bone was treated the same as in Example 1,and by such treatment, gelatin was obtained albeit poor quality.

Example 4.-Dry, acidulated bones were dis- 1 solved in 100%ethylenediamine in 48 hours at C. This solution was filtered and thendiluted with 4-6 volumes of ethyl alcohol. The precipitated gelatin wasdissolved in water, set by chilling, washed and dried.

Example 5.-Finely divided Water buffalo hide was treated with 12%methylamine solution for sixty minutes at 135 F., whereupon the hidedissolved. This solution was evacuated twentyfive minutes at a pressureof -40 mm. of mercury at a temperature of 135 F. This treatment reducedthe amine content to about 1% of the original. The pH of the solutionwas adjusted to 6.0 by the addition of a small amount of sulfuric acid.The solution was then gelled by chilling and dried.

Example 6.-Finely divided acidulated bones were agitated in a 12%ammonia solution for twenty minutes at 135 F. whereupon the acidulatedbones dissolved. Evacuation of this solution for fifteen minutes at 135F. at a pressure of 30 mm. of mercury reduced the ammonia content toless than 1% of the original. This solution gelled on cooling and wasthen dried.

Example 7.--Tne same procedure as described in Example 6 can be usedsubstituting a solution made 6% with respect to ammonia and 6% withrespect to methylamine.

Example 8.Acidulated bones were agitated in a 12% solution of ammonia,bufiered to a pH of 9.5 to 10.0 by appropriate amounts of an ammoniumsalt, such as ammonium carbonate, ammonium sulfate, ammonium acetate, orammonium chloride, for thirty minutes at 140 F. whereupon a considerableportion of the bones dissolved. Several techniques were used to recoverthe gelatin.

(a) Additional salt, i. e., (NH4)2SO4 was added, sufiicient toprecipitate the gelatin at the abovementioned pH values. This coagulatedgelatin was washed free from salts, dissolved in water, set and dried.

(b) The pH of the salt gelatin solution was lowered to the point wherethe gelatin separated from solution. This coagulated gelatin was treatedas in (a) (c) The gelatin salt solution was chilled at the pH of thereaction and the set gelatin washed free of salt before drying.

We claim:

1. A method of obtaining gelatin from collagen-containing parts of theanimal body which comprises subjecting such parts to the dissolvingaction of an aqueous solution of 1-30% concentration of an aliphaticamine selected from the group consisting of methylamine, dimethylamine,ethylamine, ethylene diamine, ethanolamine, propanolamine, and propylenediamine, whereby the collagen is dissolved and converted into gelatin.

2. A method of obtaining gelatin from collagen-containing parts of theanimal body which comprises subjecting such parts to the dissolvingaction of an aqueous solution of l-30% concentration of methylaminewhereby the collagen is dissolved and converted into gelatin.

3. A method of obtaining gelatin from collagencontaining acidulated bonewhich comprises subjecting the acidulated bone to the dissolving actionof an aqueous solution of l30% concentration of methylamine whereby thecollagen is dissolved and converted into gelatin.

4. A method of obtaining gelatin from collagen-containing animal hidewhich comprises subjecting the hide to the dissolving action of anaqueous solution of l-30% concentration of methylarnine whereby thecollagen is dissolved and converted into gelatin.

5. A method of obtaining gelatin from collagen-containing parts of theanimal body which comprises subjecting such parts to the dissolvingaction of an aqueous solution of methylamine of 130% concentration anda. buffering agent selected from the group consisting of ammonium andamine salts whereby the collagen is dissolved and converted intogelatin, separatin the resulting solution from any insoluble materialtherein followed by insolubilizing the gelatin and washing free of thesalts therein.

6. A method of obtaining gelatin from collagen-containing parts of theanimal body which comprises subjecting such parts to the dissolvingaction of an aqueous solution of 1-30% concentration of a mixture ofmethylamine and ammonia, the amount of methylamine being at least equalto the amount of ammonia, whereby the collagen is dissolved andconverted into gelatin.

R. E. DAMSCHRODER. MARIE E. KAUFFMAN.

REFERENCES CITED The following references are of record in the file ofthis patent:

